Writing instrument



FIG. 1 is a front view of a writing instrument, showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a lateral view (right side) thereof;

FIG. 6 is a lateral view (left side) thereof; and,

FIG. 7 is a perspective view thereof.

The broken lines shown in the drawings illustrate portions of the article and form no part of the claimed design. 

CLAIM The ornamental design for a writing instrument, as shown and described. 